1. Field of the Invention
This invention relates to an optical module on which a radiative device and a photo detector for detecting emitted light or the like are mounted.
2. Description of Related Art
FIG. 22A is atop view showing a conventional optical module. FIG. 22B is a side view showing a conventional optical module. FIG. 22C is a front view showing a PD element.
Referring to FIGS. 22A through 22C, reference numeral 1 denotes a substrate on which an LD carrier 3 and a PD carrier are mounted, 2 a radiative device (hereinafter referred to as an LD element, not shown), 3 an LD carrier for holding thereon the LD element 2, 4 a photo detector (hereinafter referred to as a PD element) for detecting back light from the LD element 2, 4a an incident surface of the PD element, at the peripheral of which an anode electrode 4b is provided, and on the opposite surface of which a cathode electrode is provided. Reference numeral 5 denotes a PD carrier for holding thereon the PD element 4, 5a, 5b wiring patterns laid out on the PD carrier 5, 6 a wire bonding for electrically connecting the anode element 4b of the PD element 4 to the wiring pattern 5a, and 7, 8 wire bondings for electrically connecting wiring patterns of a package (not shown) which holds thereon the substrate 1 to the wiring patterns 5a, 5b. 
In such an optical module, in case the magnitude of emitted light from the LD element 2 must be kept constant, for example, observing back light from the LD element 2 allows control of the LD element 2, as the magnitude of the back light is usually proportional to emitted light.
In order for the PD element 4 to detect back light from the LD element 2, the conventional optical module has been mounted the PD element 4 on the PD carrier 5 such that the incident surface 4a of the PD element 4 faces to the back of the LD element 2.
Outputting an electrical signal, which has a proportional relationship with back light from the LD element 2, of the anode electrode 4b of the PD element 4 and the cathode electrode, as shown in FIG. 22C, the anode electrode 4b is electrically connected to the wiring pattern 5a of the PD carrier 5 by the wire bonding. Further, the wiring patterns of the package (not shown) which holds thereon the substrate 1 are electrically connected to the wiring patterns 5a, 5b by the wire bondings 7, 8.
The conventional optical module thus configured as above involves numerous troublesome wire bonding processes required for manufacturing of an optical module. Further, the PD carrier has to be mounted to mount the PD element 4 on the substrate 1. Thus, this requirement invites a bulky and costly optical module, and asks for an additional mounting process for the PD carrier 5.